Young plants of Rhizophora mucronata Lam. were tested for oxidative stress, photosynthetic capacity and dry matter accumulation under two abiotic stress conditions; prolonged submergence and soil water stress. The experiment of prolonged submergence was performed in field conditions with two treatment levels; 50% inundation (control) and 100% inundation levels. The experiment of soil water stress was conducted in a plant-house with four treatment levels, 100% water holding capacity (WHC) (control), 50% WHC, 25% WHC and high salinity (> 35 psu). The experimentation period was 18 months. According to the results, antioxidant activity was increased in the 100% inundation level in field conditions and in the 25% WHC, 50% WHC and high salinity levels in plant-house conditions. However, decreased radical scavenging capacity reflected by low 2,2-diphenyl-1-picrylhydrazyl (DPPH) and high IC₅₀ values were only observed in the 25% and 50% WHCs. Plant cell membranes were highly damaged in the 25%, 50% WHCs and high salinity level and a significant decrease in photosynthetic capacity (~ 90% reduction) and in dry matter content of Rhizophora plants were also observed in the same treatment levels. It was recorded that a higher proportion of dry matter is allocated to the root system under the 100% inundation level and it may be an adaptation to keep up the standing stability. Although, the antioxidant and scavenging capacities of young Rhizophora plants have increased under abiotic stress conditions, oxidative stress and its associated impacts on leaf photosynthetic capacity and dry weight contents were unavoidable under persistence of the stress.

中文翻译：

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红树幼苗红树的氧化胁迫、叶片光合能力和干物质含量。在长期淹没和土壤水分胁迫下。


红树 (Rhizophora mucronata Lam) 的幼苗。在两种非生物胁迫条件下测试了氧化应激、光合能力和干物质积累；长期淹没和土壤水分胁迫。长时间淹没实验是在两种处理水平的野外条件下进行的； 50% 淹没（对照）和 100% 淹没水平。土壤水分胁迫实验在具有100%持水能力（WHC）（对照）、50%WHC、25%WHC和高盐度（> 35 psu）四个处理水平的温室中进行。试验期为18个月。结果表明，田间条件下 100% 淹没水平以及厂房条件下 25% WHC、50% WHC 和高盐水平下的抗氧化活性均有所增加。然而，仅在25%和50% WHC中观察到低2,2-二苯基-1-三硝基苯肼(DPPH)和高IC ₅₀值所反映的自由基清除能力下降。在 25%、50% WHC 和高盐度水平下，植物细胞膜严重受损，并且在相同处理水平下还观察到红树植物的光合能力（约减少 90%）和干物质含量显着下降。据记录，在100%淹没水平下，较高比例的干物质分配给根系，这可能是为了保持站立稳定性的适应。尽管在非生物胁迫条件下幼年红树植物的抗氧化和清除能力有所增加，但在胁迫持续存在下，氧化胁迫及其对叶片光合能力和干重含量的相关影响是不可避免的。